1. Field of the Invention
The present invention relates to a point-sequence approximation method of, and a point-sequence approximation apparatus for approximating a point sequence constituted of a plurality of points by a straight line and/or a curve.
2. Description of the Related Art
An approximation method of approximating position data having the form of a point sequence by a straight line and/or a curve is described in Japanese Patent No. JP-B2-2813059, for example. According to the above-mentioned approximation method, it is possible to smoothly connect two sets of approximated position data in adjacent approximation sections by selecting, from among candidates of the border point at which a straight line and a curve are connected, one that satisfies the following conditions as a border point: an angle formed between the straight line and the curve is equal to or greater than a first predetermined value; a segment ratio between the straight line and the curve is equal to or greater than a second predetermined value; and whole shape of the straight line and the curve has a convexity.
In the above-described approximation method, however, when a form of a point sequence is approximated by a straight line and/or a curve, great importance is placed on smoothly connecting the straight line and the curve in selecting the border point; accordingly, there is a possibility that the position of the approximation straight line is shifted toward the adjacent approximation curve, which can worsen approximation accuracy.